The present invention relates to a fuel evaporation gas discharge suppressing device of an internal combustion engine.
As the technique for preventing discharge of a fuel evaporation gas evaporated in a fuel tank to the air, conventionally, there are provided a canister communicating with the fuel tank and a closing valve to be controlled to seal the fuel tank in a case other than oil filling at a passage between the fuel tank and the canister. The closing valve is opened to cause the fuel evaporation gas to flow toward the canister in the oil filling and the fuel evaporation gas is thus adsorbed by the canister.
If the fuel tank is sealed by the closing valve, however, a pressure in the fuel tank is increased to be higher due to evaporation of a fuel in the fuel tank when an outside air temperature is raised.
In that case, in order to prevent discharge of the fuel evaporation gas to the air with the oil supply, the closing valve is opened when an oil filling operation is detected, and a filler port is prohibited from being opened until the pressure in the fuel tank is reduced sufficiently.
However, a long period of time is taken until the pressure in the fuel tank is reduced. For this reason, a great deal of time is required until the oil filling is started.
Consequently, there is developed the technique for opening the closing valve to discharge the fuel evaporation gas in the fuel tank to an air intake passage of an engine without adsorbing the fuel evaporation gas into the canister, thereby reducing the pressure in the fuel tank if the engine is being operated and purging is being carried out when the pressure in the fuel tank is raised (Patent Document 1).    [Patent Document 1] JP-B-4110932